Apparatus for the control of highway crossing signals



Oct. 24, 1939. E M, ALLEN 2,176,866

APPARATUS FOR THE CONTROL OF HIGHWAY CROSSING SIGNALS Filed July's, 1938 HIS ATTO R N EY Patented Oct. 24, 1939 UNITED STATES PATENT OFFICE APPARATUS FOR THE CONTROL F H IGH- WAY CROSSING SIGNALS Application July 8, 1938, Serial No. 218,131

4 Claims.

My invention relates to apparatus for the control of highway crossing signals, and has for an object the provision of novel and improved means governed by a train approach-ing the intersection for starting vthe operation of the signal in accordance with the speed of the train. Other objects and advantages of my invention will appear as the specification progresses.

I shall describe two forms of apparatus embodym ing my invention, and shall then point out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 is a diagrammatic View showing one for-in of apparatus embodying my invention. Fig. 2 is a diagrammatic View showing a modied form of the apparatus of Fig. l, and also embodying my invention.

Similar reference characters refer to similar parts in each of the two views.

Referring to Fig. 1, the reference characters l .20 and la designate the track rails of a stretch of railway over which traiiic normally moves in a direction indicated by an arrow, and which is intersected at grade by a highway H. A highway crossing signal S is located at the intersection.

Signal S may be lany one of the usual and wellknown forms of highway crossing signals, and as here shown is an audible signal in the form of an electric bell. Y

vThe track rails l and la are divided by means of" the us-ual insulated track joints 2 to form a singleY track section D-G which is provided with a track circuit comprising a suitable source of current, such as track battery 3, connected across the track rails at one end of the section, and a track relay TR connected across the rails at the other end. Track section D-G is preferably arranged for its exit end D to be adjacent highway H.

' Iwo track instruments Ml and M2 are located 40 at selected points spaced apart along the single track section D-G. These track instruments are preferably alike, and are preferably of the type having a normally closed contact which is operated to an open position in response to actuation by a passing train.v A preferred form that track instruments Ml and M2 may take is that covered in United -States Letters Patent No. 1,834,077, issued on December 1, 1931, toy A. J. Sorensen.

Track instrument M2 is located at a location E,

which location is a distance from highway H sufcient to provide a predetermined minimum operating period, at least, for signal S prior to the arrival of a train at the intersection when the train is operating at a speed not exceeding a certain prescribed speed, operation of the signal being initiated when the train reaches location E. In order to more clearly understand the apparatus embodying my invention, I shall assume location E is located in the rear of highway H a distance suiiicient to provide 15 seconds operation of the signal S prior to the arrival of a train at the intersection when a train is moving at a speed of slightly less than miles per hour, the operation of the signal being, as stated above, initiated when l0 the train reaches location E. Hence, under these conditions, the distance D-E is substantially 1300 feet in length, since a train traveling at a speed ci, say, 59 miles per hour will advance approximately 1300 feet in 15 seconds. l"

Track instrument Ml is located at a location F in the rear of location E. Location F is a distance from highway H sufficient to provide a predetermined period of operation of signal S prior to arrival of a train at the intersection when the 20 train is operating at the maximum speed for all trains, operation of signal S being initiated when the train reaches location F. In order to agree with the train speeds assumed above, I shall assume a maximum operating speed of all trains to 25 be miles per hour, and that the predetermined operating period for signal S for such maximum speed is preferably 15 seconds. Hence, under these conditions, distance D-F is approximately 1'760v feet in length, since a train operating at 80 30 miles per hour will advance approximately 1760 feet in 15 seconds.

A normally deenergized time element device, designated by the reference character TER, is provided to determine the speed of trains approach- 35 ing the intersection and to permit track instrument Ml to operate signal S when a train is traveling at a speed above the previously assumed prescribed' speed of 60 miles per hour, and 'to delay the starting of the operation of signal S until the 40 train reaches track instrument M2 when the train is traveling-at a speed less than such prescribed speed. As here shown, the device TER is a direct current slow pick-up relay which is provided with an energizing circuit passing from 45 terminal B of a suitable source of current, such as a battery not shown, through back contact 4 of track relay TR and the Winding of relay TER to terminal C of the source 0f current.

The pick-up period for relay TER may be any 50 desired interval. However, as hereinbefore mentioned, since track instrument MI initiates the operation of signal S for a train operating at a speed exceeding 60 miles per hour, relay TER cannot have a pick-up period shorter than the time re- 55 quired for a train to traverse the distance F-G, or the distance a train travels on section D-Gr prior to arriving at location F. In order to more clearly understand the apparatus embodying my invention, I shall assume that distance F--G is substantially 2600 feet in length, so that a train operating at the prescribed speed of 60 miles per hour requires approximately 30 seconds to traverse the distance. It follows that the pick-up period for relay 'I'ER will be 30 seconds. Relay TER is provided with a front contact 6 and a back contact 5, which contacts close and open, respectively,

at the expiration or" the delay period of the relay. A checking contact 'l which opens immediately upon energization of relay TER is also provided. Back contact 5 and checking contact 1 close, and front contact 6 opens, immediately upon deenergization of relay TER.

The reference character CR designates-a normally energized control relay provided With a pick-up circuit which may be traced from terminal B through front contact 8 of relay TR, checking contact 1 of relay TER, back contact 5 -.of relay TER, and the winding of relay CR to terminal C; and with a stick circuit having two branch paths, one path of which may be traced from terminal B through track instrument MI, track instrument M2, front contact 9 of relay CR and the winding of relay CR to terminal C; and the other path of which may be traced from terminal B through front contact 6 of relay TER, track instrument M2, front contact 2 of relay CR and the winding of relay CR to terminal C.

The reference character OR designates a normally energized operating relay which is energized by virtue of a simple circuit including front contact i6 of relay CR. v

Signal S is provided with a simple operating cir- `cuit including back contact l l of relay OR.

In the normal condition of the apparatus as shown in the drawing, track section D-G is unoccupied; relays TR, CR and OR are energized; and time element device TER and signal S are deenergized.

In explaining the operation of the apparatus embodying my invention, I shall first assume a train approaches highway H, in the direction of normal traiiic, at a speed of '70 miles an hour, that is, above the assumed prescribed speed of 60 miles per' hour. When the train enters track section D-G, relay TR releases to open front contact 8 and thereby open the pick-up circuit for relay CR, and to close back contact l to complete the energizing circuit for reiay TER. Since a train traveling at 70 miles per hour advances 2600 feet in approximately 26 seconds, the train will reach location F and actuate track instrument Ml prior to relay TER picking up at the end of its 30 slecond pick-up period. The actuation of track instrument Ml interrupts the stick circuit for relay CR so that relay CR becomes released to open front contacts S and iii, the latter contact opening the energizing circuit for relay OR and thereby permitting relay OR to close back contact ll to initiate the operation of signal S. Since the stick circuit for relay CR is open at front contact 9, the closing of front contact 6 of relay TER at the expiration of the slow pick-up period for relay TER, and the actuation of track instrument M2 when the train reaches location E, does not aiTect the operation of the signal for a train operating above the prescribed speed of 60 miles an hour.

When the train vacates track section D-G and clears the highway, relay TR becomes reenergized, relay TER becomes deenergized, and the pick-up circuit for relay CR is again completed so that relay CR picks up to reenergize relay OR, relay OR picking up and stopping the operation of signal S. It should be noted that the pick-up circuit for relay CR cannot be completed unless contacts 5 and l of relay TER are closed. It is to be seen, therefore, that these contacts serve to check the normal position of relay TER.

I shall vnow assume that a train approaches highway H in the direction of normal tralic at a speed of 50 miles per hour, that is, it is operating below the prescribed speed of 60 miles per hour. The entrance of the train on section D-G releases track relay TR, thereby opening the pick-up circuit ior relay CR and closing the energizing circuit for relay TER. Since the train operating at 50 miles per hour requires approximately 36 seconds to traverse the distance F-G, relay TER will pick up at the end of its 30 seconds pick-up period and close front contact 6 prior to the train arriving at location F." When the train reaches location F and actuates track instrument Mi, relay CRis held energized by virtue of its stick circuit including front contact 6 of relay TER and track instrument M2. Then, when the train reaches track instrument M2, the actuation of that instrument interrupts the stick circuit for relay CR so that relay CR releases to interrupt the energizing circuit for relay OR, which then releases and initiates the operation of signal S.

When the train clears the highway and vacates track sectiton D-G, relay TR picks up, relay TER releases, and relays CR and OR pick up to terminate the operation of signal S.

While herein described, specific values have been assumed for distances D-E, E-F and F-G, and for the pick-up period for time element device TER, it is to be understood that such values are for the purpose of illustration only and the apparatus Vcan be proportioned and adjusted, Within limits, of course, to best suitthe specificconditions of the location at which the apparatus is installed.

In Fig. 2, the apparatus of Fig, i is modied to provide directional control of the highway crossing signal, whereby a train operating in either direction over the track rails Yl and la will operate the signal when approaching the intersection. Referring to Fig. 2, the apparatus of Fig. lis modified by substituting one winding WI of an interlocking relay'XR for the track relay TR of Fig. 1, the other winding W2 of relay XR being connected across the track rails l and la of a track section D-J, which is provided on the opposite side of the intersection from section D-'E by insulating the track rails i and ia in the usual manner.V The section D-J is provided with a trackcircuit comprising a track battery 3 connected across the rails l and la at one end of the section, winding W2 being connected across the rails l and la, at the other end of the section.

The interlocking relay XR may be of any suitable type, such as,for example, that type covered by United States VLetters Patent No. 1,799,629,

granted to W. K. Lockhart and T. J. OMeara on effective to release the arma-ture of winding W2 to itsfull-released' position. Similarly, ii the lefthand win-ding W2 is first to be deenergized, the rsubsequent deenergization of winding Wl is ineffective to release its armature to the full-released position, the armature being retained `in a locked up position. Relay XR is provided with front Pflagman contacts i2 and I3, associated with windings Wiv and W2, respectively, each characterized by the iact that the contact is opened only when its associated armature is released to its fullreleased position, the contact being held closed in the locked up as well as in the picked-up position of the armature. Back contacts I4 and I5, associated with windings WI and W2, respectively, are each characterized by the fact that the contact is closed only in the full-released position of its associated armature.

For westbound traffic, that is, for traflic operating from right to left in Fig. 2, winding Wl cooperates with relay TER and track instruments Ml and M2 to control the control relay CR, and thereby govern signal S over back Contact l5 of relay CR. For eastbound traffic, winding W2 may be employed `to cooperate with a second time element relay and two track instruments provided for section D-J, to control a second control relay and thereby govern signal S over a back contact of the second control relay. The second time element relay, the second control relay, and the two track instruments for section D-J are not shown in Fig. 2 for the sake of simplicity, it being understood that the circuits controlling each element will be substantially similar to the circuits controlling the corresponding elements TER, CR, and instruments Ml and M2 of Fig. 2.

The operation of the apparatus of Fig. 2 in governing signal S is similar to the operation described in detail in connection with Fig. 1, as may readily be understood by an inspection of Fig. 2, and it is believed, therefore, that this latter operation will be apparent from the foregoing description without further detailed description, except to point out that whenever Winding WI or W2 as the case may be, is deenergized by a train receding from the intersection through its associated section, that Winding is prevented from governing its associated control relay by virtue of the interlocking feature of relay XR, with the result that operation of the signal is effected over a back contact of one of the control relays only when a train approaches the intersection. It should be noted that when the train recedes from the intersection, the actuation of the track instruments associated with the track section on the receding side of the intersection does not affect the operation of signal S, since the control relay for that section is held energized over a front "flagman contact of winding WI or W2.

One advantage of apparatus embodying my invention is the provision of means for initiating the operation of a highway crossing signal in accordance with the speed of a train approaching the intersection, whereby a minimum operating period is assured for a fast moving train, and an undesirably long operating period is not eiiected by a slow moving train.

Although I have herein shown and described only two forms of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

l.. In combination, stretch of railway track intersected by a highway and provided with an insulated track section to one side of said intersection, a highway crossing signal located at said intersection, a track circuit for said track section including a track relay, two track instruments located one each at spaced points along said track section, a control relay, a pick-up circuit for said control relay including a front contact of said track relay, a stick circuit 'for said control relay governed by each oi said two track instruments, operating means controlled by said control relay for operating said signal, a normally deenergized time element device, an energizing circuit for said time element device including a back contact of said track relay, and means governed by said time element device for at times rendering the track instrument more remote from the intersection ineffective to govern said stick circuit for said control relay.

2. In combination, a section of railway track intersected by a highway and provided with a track circuit including a track relay, a highway crossing signal located at said intersection, a irst track instrument located at a selected point along said section, a second track instrument located along said section intermediate said intersection and said iirst track instrument, a control relay, a pick-up circuit for said control relay including a iront contact or" said track relay, a iirst stick circuit for said control relay including a normally closed contact of each of said iirst and said second track instruments, a normally inactive time element device, means including a back contact of said track relay to render said time element device active, a second stick circuit for said control relay including a Contact of said time element device closed in a predetermined time interval and also including the normally closed contact of said second track instrument, and operating means governed by said control relay for operating said signal.

3. In combination, a stretch of railway track intersected by a highway and provided with a single insulated track section located with its exit end adjacent the highway, a highway crossing signal located at said intersection, a track circuit including a track relay or said track section, a time element device having a normal position and an operated position and provided with a contact closed only in the operated position of Said device, circuit means governed by said track relay for controlling said time element device from its normal position to its operated position, two track instruments located spaced apart along said section, a control relay normally energized over a stick circuit controlled by each of said two track instruments, a pick-up circuit ior said control relay controlled by said track relay, circuit means governed by the contact of said time element device effective at times to render the track instrument more remote from the intersection ineffective to control the stick circuit oi said control relay, and means controlled by said control relay for causing said signal to operate.

4. In combination, a stretch of railway track intersected by a highway and provided with a single insulated track section located with its exit end adjacent said highway, a highway crossing signal located at said intersection, a track circuit including a track relay for said track section, a time element device having a normal position and an operated position, said device being provided with a checking contact closed only in the normal position of said device, said device also being prothev checking contact of said time element device, circuit means controlled by the time contact of said element device eiective at times to render the track instrument more remote from the intersection ine'ective to control the stick circuit of said control relay, and means controlled by said control relay for causing said signal to operate.

EARL M. ALLEN. 

